The HMRC webpage link below allows you to check what you need to do after 31 July 2020 if you choose to defer your second payment on account for the 2019 to 2020 tax year.
You had the option to defer your second payment on account if you were:
• registered in the UK for Self-Assessment and
• finding it difficult to make that payment by 31 July 2020 due to the impact of coronavirus
You can still pay your deferred July 2020 payment on account any time up to 31 January 2021. There will be no interest or penalty as long as you pay in full by that date.